Setting up an X.500 Directory Service

One of the more difficult aspects of using electronic mail is finding the address of the person you want to talk to. At present there is no complete solution to this problem: a global directory is needed. The X.500 standard describes a distributed directory service that has the potential to solve this problem. There are now several implementations of X.500 and the Directory is developing into a useful international service. This paper introduces the X.500 system, and describes Brunel’s experience with setting up and running a directory service based on ISODE/Quipu. Software configuration is briefly discussed and the data-gathering process is described. Suggestions are given for merging data from several sources to form coherent directory entries. 1. The Need for a directory How often have you come back from a conference half-remembering somebody’s name and then wanted to contact them? How many times do you refer to your organisations internal phone book each week? How many people come to you each week wanting to know the electronic mail address of somebody at a site you have never heard of? Directories are a part of life. The problem (as with standards) is that there are so many to choose from. Just finding out what directories exist can be difficult; a directory of directories would be a useful thing! Better still would be a single directory service, covering the whole world and listing everything that every existing directory contains. This single Directory would of course be totally user-friendly and would do exactly what was expected rather than what was asked for! This of course is impossible, but it is a reason-able description of what X.500 is trying to do. 2. The Scale of the Problem To be really useful, the Directory must contain information on every person in the World. Ultimately there will probably be three entries for each person: • Residential person • Organisational perso